The present invention relates to a method of fabricating a highly integrated semiconductor apparatus, and more particularly, to a fabricating method which can improve integration, operating characteristics and semiconductor chip yield.
In general, a semiconductor is a material belonging to an intermediate region between a conductor and insulator. Although the semiconductor is similar to the insulator in a pure state, its electrical conductivity can be increased by the addition of impurities or other manipulation. The impurity is added to the semiconductor and a conductor is connected thereto to generate a semiconductor device such as a transistor. An apparatus with various functions fabricated using the semiconductor device is a semiconductor apparatus. A representative example of the semiconductor apparatus is a semiconductor memory apparatus.
The semiconductor memory apparatus includes a plurality of unit cells, each of which is composed of a capacitor and a transistor. The capacitor is used to store data. The transistor is used to transfer data between a bit line and the capacitor, corresponding to a control signal (word line). The transistor is composed of three regions, i.e. a gate, source and drain. A control signal input to the gate causes electric charges to move between the source and the drain. The movement of the electric charges occurs through a channel region. This channel uses the properties of the semiconductor to conduct a current.
In a case where a general transistor is formed on a semiconductor substrate, a gate is formed on the semiconductor substrate, and an impurity is doped into both sides of the gate to form a source and a drain. In this case, a space between the source and the drain below the gate becomes a channel region of the transistor. The transistor having this horizontal channel region occupies a certain area of semiconductor substrate. In the case of a complicated semiconductor memory apparatus, it is difficult to reduce the overall area due to a plurality of transistors included therein.
If the total area of the semiconductor memory apparatus is reduced, the number of the semiconductor memory apparatuses that can be produced per wafer can be increased, which leads to higher productivity. A variety of methods have been suggested to reduce the entire area of the semiconductor memory apparatus. One of the methods is to use a vertical transistor having a vertical channel region, instead of using the conventional horizontal transistor having the horizontal channel region.